Are Big Ben's bongs about to fall silent?

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Photos:Ringing the changes: Renaming 'Big Ben'

Ringing the changes: Renaming 'Big Ben' – British lawmakers want to rename St Stephen's Tower -- known to tourists around the world as "Big Ben" -- after Queen Elizabeth II.

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Photos:Ringing the changes: Renaming 'Big Ben'

Ringing the changes: Renaming 'Big Ben' – The Queen, seen here addressing both Houses of Parliament in Westminster Hall, is celebrating her Diamond Jubilee in 2012.

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Photos:Ringing the changes: Renaming 'Big Ben'

Ringing the changes: Renaming 'Big Ben' – MP Tobias Ellwood says naming the tower, seen here in the background of the coronation parade, after the monarch would be a fitting way to mark her 60th year on the throne.

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Photos:Ringing the changes: Renaming 'Big Ben'

Ringing the changes: Renaming 'Big Ben' – "Big Ben" is one of London's most famous landmarks. The four glass clock faces on the tower, each measuring seven meters in diameter, are cleaned by a team of experts once every five years.

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Photos:Ringing the changes: Renaming 'Big Ben'

Ringing the changes: Renaming 'Big Ben' – Big Ben is actually the name of the 13.5 ton bell inside the tower. The clock came into operation on 31st May 1859; Big Ben rang out for the first time later that year.

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Photos:Ringing the changes: Renaming 'Big Ben'

Ringing the changes: Renaming 'Big Ben' – Ellwood said that if the renaming plans were given the go-ahead, he hoped the Queen would not have to climb the 334 steps to the belfry for an official ceremony.

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Photos:Ringing the changes: Renaming 'Big Ben'

Ringing the changes: Renaming 'Big Ben' – It remains to be seen whether the new name, Elizabeth Tower, will be widely used, or if the public will stick with the old nickname. Jokers have suggested meeting half way, with the new nickname 'Big Beth'.

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Story highlights

The Great Clock at London's Houses of Parliament is in urgent need of major repairs

Lawmakers fear Big Ben's famous "bongs" may fall silent if the timepiece is not refurbished

The clock began keeping time in 1859; it has been shut down for repairs several times

London (CNN)The bongs of Big Ben have echoed across London for more than 150 years, thrilling tourists who throng the pavements below, jostling to have their photographs taken alongside the iconic monument.

But the days of setting your watch by the Great Clock could be in jeopardy: the timepiece atop the Houses of Parliament's Elizabeth Tower is badly in need of repair.

And British lawmakers have warned the clock may stop altogether if it is not refurbished -- at a cost of $45 million (£29 million) -- in works that would see it shut down for four months.

Big Ben is the name of the bell inside the tower (St. Stephen's Tower, renamed Elizabeth Tower in 2012), and not the building or the clock (simply known as the Great Clock) itself.

According to a parliamentary report seen by both the Mail on Sunday and Sunday Times newspapers: "The clock currently has chronic problems with the bearings behind the hands and the pendulum.

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"Either could become acute at any time, causing the clock to stop -- or worse." One source told the Mail on Sunday they believe "or worse" means that the clock's heavy hands could fall off.

Photos:12 of the world's most beautiful clocks

Photos:12 of the world's most beautiful clocks

Philadelphia City Hall – Philadelphia City Hall, PhiladelphiaCompleted: 1901Height: 167 meters (548 feet)Chief architect: John McArthur, Jr.Observation deckWhile ascending to the Philadelphia City Hall'sobservation deck in a tiny elevator, visitors can see the internal workings of the tower, the four big clocks as well as views away from the tower. Special featuresStanding on the top of the tower is a 37-feet-high bronze statue of William Penn, the founder of Pennsylvania and planner of Philadelphia. Next to Penn are four smaller bronze statues depicting the first people in Philadelphia -- immigrants from Sweden and Native Americans.More facts on Philadelphia City Hall in the next slide.

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Photos:12 of the world's most beautiful clocks

Philadelphia City Hall – Philadelphia City Hall, PhiladelphiaPlanned 200 years before ground was broken, Philadelphia City Hall was designed to be the tallest structure in the world. But construction took so long (1871-1901) that the Eiffel Tower (301 meters) was completed first. It remained the tallest occupied building until 1908 and it's still the biggest city hall in the United States in terms of floor space.Philadelphia City Hall, Broad Street and Market Street, Philadelphia

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Photos:12 of the world's most beautiful clocks

Old Town Astronomical Clock (Prague) – Old Town Astronomical Clock, Prague, Czech RepublicCompleted: 1410Height: 59 meters (193 feet)Builders: Co-built by clockmaker Mikulas of Kadane and Jan Sindel, a mathematics and astrology professor at Charles University in Prague.Observation deckFor $5, visitor can tour the tower and access the observation deck, which sits above the clock.Special featuresEach hour from 9 a.m. to 9 p.m., models of the Twelve Apostles are set in motion. Each has a distinctive feature -- St. Peter for example is holding a key (to the Kingdom of Heaven). Other figures standing next to the dial include a Grim Reaper and a man looking into a mirror, representing mankind's vanity.More on Prague's Old Town Astronomical Clock the next slide.

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Photos:12 of the world's most beautiful clocks

Old Town Astronomical Clock (Prague) – Old Town Astronomical Clock, Prague, Czech RepublicLegend claims the clock's maker, Mikulas of Kadane, was blinded by city officials after completing this clock, so he couldn't build another. An informative website for the Old Town Hall explains how to read the astronomical clock (tracking time is a secondary function) and includes facts such as, "if it is a leap year, the wheel does not move one night."Astronomical Clock at Old Town Hall, Staromestske nam. 1/3, Prague 1 - Old Town, Prague, Czech Republic

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Photos:12 of the world's most beautiful clocks

Ferry Buliding Marketplace (San Francisco) – Ferry Building Marketplace, San FranciscoCompleted: 1898Height: 75 meters (245 feet)Architect: A. Page BrownSpecial featuresThe building beneath the clock tower serves as a marketplace with a farmers market, shops and restaurants. Free walking tours start at noon on Saturdays and Tuesdays, coinciding with the farmers' market.Tough historySan Francisco's Ferry Building survived the city's two major earthquakes in 1906 and 1989. The Ferry Building became near obsolete after the opening of Bay Bridge and Golden Gate Bridge. In 1957 the double-deck Embarcadero Freeway was built, blocking the face of the building. It wasn't until the 1989 Loma Prieta earthquake that the freeway was damaged and removed and the facade was visible again.Ferry Building Marketplace, 1 Sausalito, San Francisco

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Photos:12 of the world's most beautiful clocks

Old Port Clock Tower (Montreal) – Old Port Clock Tower, MontrealCompleted: 1922Height: 45 meters (148 feet)Observation deckFree to access between May and September with 192 steps to ascend.Special featureFrom May to September, a temporary urban beach opens at the base of the Clock Tower. The beach has a restaurant, a bar, showers and live entertainment at night. There's no direct access to the water, due to strong currents.More on the Old Port Clock Tower on the next slide.

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Photos:12 of the world's most beautiful clocks

Old Port Clock Tower (Montreal) – Old Port Clock Tower, MontrealThe tower is lit at night with bright lights that highlight its white coloring. The clock mechanism was built in London in 1921 by Gillett & Johnson, the company that designed the mechanism in the clock tower in the Palace of Westminster in London. Space was reserved next to the clock for a bell to ring each hour, but it was never installed.The tower also honors men of the merchant navy lost at sea during World War I.Old Port of Montreal, 333 Rue de la Commune Ouest, Montreal

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Photos:12 of the world's most beautiful clocks

Zytglogge Tower (Bern, Switzerland) – Zytglogge Tower, Bern, SwitzerlandCompleted: 1405 (rebuilt in 1527)Height: 16 meters (52 feet)Observation deckA 50-minute tour ($16) starts daily at 2:30 p.m. Reservation required.Special featuresFigurines next to the clock rotate, and every hour a larger figure appears to hammer the gilded bell that rings at the top of the tower. Apart from time, the astronomical clock also features a lunar dial, 12 zodiac signs, a calendar dial and a planisphere (star chart).Historic usesThe Clock Tower served as Bern's first western city gate during the city's expansion around 1220. It was transformed briefly into a prison before becoming a clock tower.Bern's Clock Tower (Zytglogge), Bahnhofplatz 10a, 3011 Bern, Switzerland

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Photos:12 of the world's most beautiful clocks

Spasskaya Tower (Moscow) – Spasskaya Tower, MoscowCompleted: 1491 (official year for the inauguration of the clock is unconfirmed)Height: 71 meters (232 feet)Architect: Pietro Antonio SolariSpecial featureThe clock chimes a short tune every 15 minutes.Stalinist touchThe star was added to the tip of the roof by Joseph Stalin to replace the golden eagles, a symbol of Tsarist Russia. The tower is a part of the Kremlin wall that encloses cathedrals, palaces, a square, the official residence of the country's president and a helipad.Spasskaya Tower, Moscow Kremlin Museums, Krasnaya ploshad, 3, Moscow, Russia

Munich Glockenspiel (Munich) – Munich Glockenspiel, Munich, GermanyCompleted: Around 1900Height: 85 meters (255 feet)Architect: Georg HauberrisserSpecial featuresThe clock rings daily at 11 a.m., noon and 5 p.m. (from March to October), with a 12-minute show featuring 43 bells and 32 life-sized figures. The show includes the story of the wedding of Duke Wilhelm V and Renata of Lorraine, a jousting tournament and a traditional "coopers' dance" performed by the city's barrel makers. The clock is now part of the new town hall in Munich.Munich Glockenspiel, Marienplatz 8, 80331 Munich, Germany

Sultan Abdul Samad Building's Clock Tower (Kuala Lumpur} – Sultan Abdul Samad Building's Clock Tower, Kuala Lumpur, MalaysiaThe clock tower marked the country's independence at midnight on August 31, 1957, when the Malaysian flag was hoisted for the first time. Jalan Raja (the main road in front of the Sultan Abdul Samad Building) is closed during nights of special occasions, making it easier for the public to get closer to the building. Sultan Abdul Samad Building, Jalan Raja, Merdeka Square, Kuala Lumpur, Malaysia

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Photos:12 of the world's most beautiful clocks

Osaka Station City's Water Clock (Osaka) – Osaka Station City's Water Clock, Osaka, JapanCompleted: 2011Designer: Mitooka EijiSpecial featureA mesmerizing water display (see video on Youtube) is the highlight of this building. As well as displaying the time, the water clock shows various graphics including cherry blossoms, tulips, fireworks and goldfish.'Spacey' factThe clock draws patterns by controlling with a computer the length of the water threads spilled from hundreds of small tubes. It's a patented technology developed by KOEI Co., Ltd., called "Space Printer."Osaka Station City, Umeda, Kita Ward, Osaka, Japan

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Photos:12 of the world's most beautiful clocks

Chiang Rai Clock Tower (Thailand) – Chiang Rai Clock Tower, Chiang Rai, ThailandCompleted: 2008Designer: Chalermchai Kositpipat Special featureStanding as the centerpiece of a roundabout in the city, the golden tower puts on an audio and light show every night at 7, 8 and 9 p.m. The tower was designed by Thai artist Chalermchai Kositpipat, who also built the White Temple in Chiang Rai.Chiang Rai Clock Tower, Phaholyothin Road and Banpaprakan Road, Chiang Rai, Thailand

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Photos:12 of the world's most beautiful clocks

Big Ben, The Elizabeth Tower (London) – Big Ben, The Elizabeth Tower, Palace of Westminster, LondonCompleted: 1859Height: 96 meters (315 feet)Special tourTour is only available to UK residents who have arranged it through their local MP or a Member of the House of Lords. Special featureThe four clock dials each feature a Latin inscription that translates to "O Lord, save our Queen Victoria the First." More facts on the next slide.

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Photos:12 of the world's most beautiful clocks

Big Ben, The Elizabeth Tower (London) – Big Ben, The Elizabeth Tower, Palace of Westminster, LondonBig Ben, originally the name of the biggest bell that chimed the hours, cracked two months after its first chime and remained silent for the next four years. In 1863, the bell was turned so an undamaged portion is now struck with a smaller hammer. The crack remains there today. There's a prison room in the tower that was used once to lock up a Member of Parliament. In 1880, Charles Bradlaugh had just been elected, but refused to swear allegiance to the monarch on a Bible. He was kept in the room for a night. Big Ben, The Elizabeth Tower, Westminster, LondonMORE: Big Ben fast facts

Each of the timepiece's four 9ft long (2.7 meter) hour hands are made of gunmetal, and weigh in at 660 pounds (300kg) each. The minute hands, made of copper and almost 14ft long (4.2 meter), are lighter, weighing 220lb (100kg) each.

In its plea for emergency funding for the repairs, the report is understood to have claimed the clock is a "symbol of democracy" and warned that a breakdown would cause "international reputational damage."

Speaking to CNN, a parliamentary spokesman refused to go into detail about the repairs needed -- or how much they would cost.

"A feasibility study and survey work has been carried out on the Elizabeth Tower in order to understand in detail the condition of the building fabric, the clock mechanism, and the building services," he said.

"Committees of both Houses are currently considering the study and will provide advice [on] how best to proceed. No decisions on works, timescales or costs have been agreed."

The clock first began keeping time in 1859, but Big Ben's chimes fell silent three months later when the bell cracked; four years later the bell was turned to allow it to ring out once more.